HELP...seized old 403

[Bandit one]

I recently had time to finally work on my 79 T/A after sitting outside (covered) for 6 years. When i first bought the car all i did was throw in a battery just to see if the engine turned over and it did......that was 6 years ago. Now i tried to turn the engine over with the battery power (new) again and no such luck. I took out all the plugs and put some deep creep and wd40 into the cylinders and tried to turn it over with a swing bar....no luck. What else can i do to try and free up this engine? Is the engine toast now???!!! The guy i bought it from said it ran good before i bought it. Thanks in advance!

[Grand73Am]

I think it's salvageable. I'm driving one now that was left outside, uncovered for 6 years, and it was a rusty mess. I had to replace some rusty top end parts, but otherwise the bottom end is still good and it doesn't even smoke. So, I'd think your covered car has a good chance.
I would put some PB Blaster in the cylinders. You can find it in the gallon size at a parts store, and pour it into each spark plug hole until the cylinders are full to the bottom of the plug holes. Let it sit  for 24 hours. Then with your breaker bar, work the crank back and forth a little at a time. It should gradually loosen more and more until it will rotate completely.
I've used a product called Kroil to do this before, but you have to order Kroil. I believe PB Blaster will do just as well, if not better, and it's available locally.